This invention relates to the biological and non-biological treatment of water or wastewater which requires supplemental elements (such as oxygen, nutrients, or air) to catalyze or generally enhance treatment of the water volume, as well as any byproducts of such treatment. Byproducts may include, for example, odorous gases or wastewater sludge and the associated supernatant, which is the liquid lying above the digesting sludge mass within the treatment basin. An example of treatment would be the introduction of an oxygen infused water into a sludge digester basin primarily to improve odor, and/or biological and mechanical (settleability) treatment, although other benefits may be achieved if the oxygen level is sufficient and sustained in the targeted medium.
Maintaining the required oxygen level effectively is a wastewater industry challenge and the aeration process is typically the largest energy user associated with wastewater plant operations. Historically the typical aeration process is relatively inefficient in providing for oxygen transfer and the typical oxygen transfer mechanisms require substantial energy to process this oxygen with multiple delivery system components each requiring extensive maintenance. Historically, energy costs associated with wastewater aeration can account for 90% of all energy consumed at a wastewater treatment facility. The present invention provides a very efficient, low energy, low maintenance method of delivering oxygen via gas (oxygen) infused liquid (water) to the digestion process.
The digestion process is important for sludge stabilization and is a critical component in wastewater treatment. Aerobic digestion is the process of oxidizing and decomposing the organic component of wastewater sludge by microorganisms in the presence of oxygen. Aerobic digestion stabilizes sludge, reduces biological mass and volume, and reduces vector attraction and pathogenic organisms. Aeration can bring about the physical removal of odor-producing substances in the wastewater, such as hydrogen sulfide (H2S) and other volatiles as well as non-volatiles through oxidation and settling.
Oxygen transfer is the process by which oxygen is conveyed from the gaseous phase to the liquid phase. Typical equipment used to deliver oxygen for the digestion process has been surface mechanical type aerators or diffused aeration systems which take atmospheric air (approximately 21% oxygen) and deliver it to the medium via bubbles with a diameter in the range of 0.3 mm and larger.
Mechanical aerators break the surface of the basin liquid allowing the introduction of atmospheric air and ultimately oxygen from this air to enter the basin liquid. This method of providing oxygen to the medium is inefficient and does not promote solids settling in the supernatant column.
Diffused aeration systems include a low pressure, high volume air compressor (blower), air piping system and diffusers that break up the air by dispersing bubbles throughout the aeration tank. The oxygen transfer is directly related to the surface area of these bubbles and the ability for oxygen to transfer from the area of contact. The diffusion of air can be accomplished with several types of diffusers which are normally located near the tank bottom and can include fine bubble and coarse bubble diffusers. In addition to inefficient oxygen transfer these diffusers are plagued with plugging which is especially evident in digesters whose operation includes periodic settling and supernatant removal. This situation is due to typical diffuser installation located on the basin floors and when air is turned off the sludge and sediments can enter the air piping and adhere to the inner walls of the piping and diffusers.
When the word infused is used it means a gas that is infused, enriched in, mixed or combined with a liquid and able to stay as such to complete the task.
When the word oxygen or gas is used it includes: dissolved, micro and/or nano bubbles.
Nozzles or applicators can also include generators if the generators are within the basin, giving direct application (in a controlled fashion) and attached to the delivery system.
When the word oxygen is used it means oxygen or any gas able to accomplish the same, similar, or intended results as disclosed herein.
The foregoing discussion reflects the current state of the art of which the present inventors are aware. Reference to, and discussion of, this information is intended to aid in discharging Applicant's acknowledged duty of candor in disclosing information that may be relevant to the examination of claims to the present invention. However, it is respectfully submitted that none of the above-indicated information discloses, teaches, suggests, shows, or otherwise renders obvious, either singly or when considered in combination, the invention described and claimed herein.